JPS63266000A - Production of regenerated leather - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing recycled leather using shaving waste from chrome-tanned leather generated during the bookbinding process.

[Prior art]

A slurry containing an aqueous anionic resin emulsion adhesive mixed with an aqueous dispersion of open fibers whose main component is chrome-tanned shaving waste is wet-formed into a sheet, which is then dried to fully produce recycled leather. are publicly known (Japanese Patent Publication Nos. 59-560, 59-33,160, 154,500/1980, 93,800/1980, 149,566/1987).

In these known techniques, the anionic resin emulsion not only functions as an adhesive but also provides water resistance and moldability to the resulting recycled leather.

However, in general, chrome-tanned shaving waste is often tanned with cationic chromium salts, and because the carboxyl groups (-blocked and basic groups of the skin are activated), there are anionic shavings. When a resin emulsion adhesive is added, the anionic adhesive and shaving debris bond very quickly, and the adhesive rapidly bonds on the surface of the leather fibers, making it difficult to use the adhesive as a medium. Agglomerates are formed, making papermaking by the wet process virtually difficult.

Therefore, as a method for preventing agglomeration when a chromium-tanned shaving waste aqueous dispersion and an anionic resin aqueous emulsion are mixed, the above-mentioned patent publications are disclosed in Patent No. 59-33.
, No. 160, the chrome tanning layer of 50 to 95 layers,
It is said that wet papermaking is possible by adding an anionic resin emulsion to a mixture of 5 to 50% fine asbestos or cationic fine inorganic fibers in water. This is because the anionic resin emulsion is first agglomerated on the surface of the cationic inorganic fibers, and the mold release of the agglomeration with the tin wheel is reduced.

With this method, there is a change in quality because it is necessary to add ingredients other than leather.

In JP-A No. 57-149,566, latex is added to leather scraps.
(emulsion excluding acrylic) is added to form a sheet, but the acrylic resin emulsion with Nanion activation causes aggregation in chrome tanned leather. However, acrylic resin has hardness, flexibility, weather resistance,
It has superior durability compared to latex.

JP-A-57-154,500 and JP-A-58-93,800 disclose a method in which shaving waste is defibrated and beaten in the presence of an anionic acrylic ester resin emulsion and then formed into a sheet when mixed with papermaking fibers. , Patent 59-5
In No. 60, an attempt was made to eliminate the non-uniformity between the binder and the leather fibers by adding a coagulant to the resin to form an aggregate slurry in advance and mixing this with the multilayer slurry. There are problems with the complexity and uniformity of the process.

[Specific measures to solve the problem]

In the present invention, the carboxyl group concentration in the anionic resin aqueous emulsion was set to 1.4 X 1 o-mol or less in order to prevent rapid aggregation during mixing with the anionic resin aqueous emulsion.

That is, the present invention relates to a chromium-tanned shaving waste defibrated material and an anionic resin containing a carboxyl group (-COOF() based on lβ-unsaturated carboxylic acid) in a ratio of 1.4 x 10- or less moles. This paper proposes a method for producing recycled leather from a slurry containing an aqueous emulsion.

(Shaving waste) Chrome-tanned shaving waste has a uniform particle size, and is defibrated in a dry state using a beater such as a beater or refiner, or defibrated in water using a beater. A portion of the shaving waste may be replaced with a tanned layer, pulp fiber, inorganic fiber, or resin fiber.

This fully defibrated shaving waste becomes slimy like gruel in water. An anionic resin aqueous emulsion is added to the shaving waste and water mixture.

(Anionic resin aqueous emulsion) An anionic resin aqueous emulsion that imparts shape retention, water resistance, flexibility, or rigidity to recycled leather is made by combining a vinyl phosphor containing an unsaturated carboxylic acid with sodium dodecylbenzenesulfonate, A co-conjugate obtained by emulsion polymerization in the presence of 0.1 to 5 mt'Z of an anionic surfactant such as sulfuric half ester of p-nonylphenol, 0 to 5 weight range of nonionic surfactant, and calcium persulfate. acid group (-CO
OH) is a resin emulsion of 1.4 x 10 moles or less.

As a vinyl monomer, methacryl tRn/propyl (T
g81℃), styrene (100℃), acrylonitrile (100℃), methyl methacrylate (105℃), methacrylic acid (130℃), itaconic acid (130℃), acrylamide (153℃), 2-ethylhexyl octoacrylate (Tg -85℃), acrylic fin/butyl (-54
°C], ethyl acrylate (-22 °C), inpropyl acrylate (-5 °C), 2-ethylhexyl methacrylate (-5 °C), n-propyl acrylate (8 °C), n-butyl methacrylate (20 °C) ℃), vinyl acetate (30℃),
t-Butyl acrylate (45°C), 2-hydroxyethyl methacrylate (55°C), ethyl methacrylate (65°C)
), isobutyl methacrylate (67℃), vinyl chloride (79℃), vinylidene chloride (-18℃), ethylene, etc. are used alone or in combination of two or more (the numbers in parentheses indicate the This is the glass transition point of a vinyl monomer homofiltrate).

The type and amount of these polymers to be used are determined by taking into account the usage temperature of the resulting emulsion and using the glass transition point of the resulting resin as a guide.

In the present invention, it is preferable to use an emulsion crab in which the film forming temperature is 30° C. or lower from the viewpoint of film formation, and the film forming temperature is 30° C. or higher in consideration of the hardness of the film, stains due to stickiness, etc.

In addition, when trial manufacturing recycled leather, the glass transition point is 40
An aqueous emulsion of the resin at ~120°C is preferred. In this case, it is preferable that the fiber length of the multilayer is long. Moreover, emulsion resin concentrations ranging from 20 to 55 weight range are usually used. Further, antifoaming agents, dispersants, thickeners, antifreeze agents, film forming aids, plasticizers, additives, etc. may be added to the emulsion.

A preferable resin aqueous emulsion includes (a) 0 to 1.0% by weight of α,β-unsaturated carboxylic acid (b) acrylic acetic acid alkyl ester (the number of carbon atoms in the alkyl group is 2 to 8) 40 to 551ti (C ) selected monomers of methyl methacrylate, styrene and acrylonitrile (d) N-phenylmaleimi), N-me-IF-0-
The vinyl monomers l to xOi carried by lyacrylamide, acrylamide, methacrylamide, and 2-hydroxyalkyl acrylate (the alkyl group has 2 to 4 carbon atoms) are the anionic 0.1 to 5 parts by weight of a sexual emulsifier and 0 to 5 parts by weight of a nonionic emulsifier
The film-forming temperature obtained by emulsion polymerization using a polymerization catalyst such as calcium persulfate in the presence of 5 parts by weight is 2°C or lower.

Component (a), σ, β-unsaturated carboxylic acid, improves adhesion to shaving debris, so it is preferable that it be present as much as possible; however, if it is present in large amounts, gelation problems may occur.

Such α,β-unsaturated carboxylic acids (including their anhydrides)
Examples of carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, etc., but as a result of the study in the present invention, the amount of carboxylic acid greatly affects miscibility and storage stability. The amount of carboxyl groups based on the α,β-unsaturated carboxylic acids occupied is preferably not more than 1.4 X 10 mol! , OX 10"" ~ 1.2 X 1
Make it 0 mol.

Component (b), acrylic acid alkyl ester, is a monomer that gives flexibility to the film, and includes ethyl acrylate, inglovir acrylate, n-butyl acrylate, t@butyl acrylate, n-propyl acrylate, and diacrylic acid. -Ethylhexyl etc. are used.

Component (C), methyl methacrylate, acrylonitrile, or styrene, is a hard monomer that imparts toughness to the film, and some of these may be replaced with ethyl methacrylate, inglovir methacrylate, or isobutyl methacrylate.

Component (d), a vinyl monomer having an 10H group, a -CONH2 group, and a methylol group, has good adhesion to shaving debris, similar to the carboxyl group.

The stability of anionic resin aqueous emulsions usually decreases due to the mixing of cations and ions, but in the invention of the previous application ← Japanese Patent Application No. 61-251163), the stability of anionic resin aqueous emulsions is improved when mixed with a cationic emulsifier, which is a cationic ion. Although this objective was achieved by incorporating an amphoteric active agent, the type and amount of the amphoteric emulsifier and the mixing procedure are limited.

In the present invention, as a result of repeated studies on a method of directly mixing cations and ions without using an additive stabilizer, we found that 1000H (carboxylic acid: JIie) in the copolymer
This purpose can be achieved by limiting the content.

Anionic resin aqueous emulsion is shaving waste 1
It is used in a proportion of 8 to 50 parts by weight, preferably 12 to 20 parts by weight, based on the resin solid content.

If it is less than 8 parts by weight, the contribution to improving water resistance is small.

On the other hand, if it exceeds 50 parts by weight, it will not look like leather but will become hard like a resin board.

The resulting recycled leather may be colored by adding dyes and pigments to the emulsion. Further, from the viewpoint of the efficiency of coating the resin component onto the pulley during paper making, a coagulant may be added.

Embodiments Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that the intermediate parts and sections are based on weight unless otherwise specified.

Emulsion production example 1 Temperature controller, squid-shaped stirrer, reflux condenser, supply container,
The following raw materials were charged into a reaction vessel equipped with a thermometer and a nitrogen inlet tube.

200 parts of water 35 parts aqueous solution of the sodium salt of the sulfur ff2 half ester of p-nonylphenol (anionic emulsifier) reacted with 20 moles of ethylene oxide 5 parts 20 parts of p-nonylphenol (nonionic emulsifier) reacted with 25 moles of ethylene oxide 20 parts of solution.

Next, after purging the inside of the reaction vessel with nitrogen gas, 10 parts of Feed I shown below were added, and the mixture was heated to 90°C.

Feed I Water 200 parts 35% aqueous solution of the above anionic emulsifier 25 parts Methyl methacrylate 195 parts Acrylic eRn
-Butyl 189 parts acrylic acid
8 parts acrylamide
Part 8.

Furthermore, after charging 10% of 2.5 parts of potassium persulfate dissolved in 85 parts of water (Feed ■) into the container, all of the remaining Feed ■ and 40 parts of Feed H were The mixture was fed into the container over a period of 5 hours, and after the feeding was completed, the feed was kept at the same temperature for 2 hours to polymerize the feed (2) to obtain an aqueous anionic resin emulsion.

Examples 2 to 12 Anionic resin aqueous emulsions were obtained in the same manner as in Example 1, except that the composition of the vinyl monomer was changed as shown in Table 1.

(The following is a blank space) Example 1 Shaving waste from chrome tanning, which is a waste material generated by the leather manufacturing industry, was ground into a predetermined granule using a super mixer, and then charged into a Niagara beater at a concentration of 44. Beating and defibration were performed using a Niagara beater for 40 minutes.

Water was further added to this beaten solution to give a concentration of 2 g.

The anionic aqueous emulsion (solid content concentration 50%, pH 7.5) obtained in Production Example 3 with a film-forming temperature of 20° C. and a carboxyl group content of 6.94×10 mol was added to the beating solution, followed by shaving. The waste was mixed under stirring to obtain a papermaking raw material slurry such that the amount of waste was 20 weight ft (resin solid content).

The state of dispersion of wood chips during the elapsed time after the preparation of this papermaking raw material slurry was as follows.

Immediately Good, paper can be made after 3 hours
Good, 1 Stored at 50℃ for 1 day Good, 〃 Stored at 50℃ for 2 days Good, 1 Stored at 50℃ for 7 days Good, paper making possible After adding 8-sulfuric acid band to this papermaking raw material slurry and adjusting the pH to 4, This was made into paper using a Fourdrinier multi-tube paper machine, dehydrated by press, and further dried in dry air to obtain recycled leather with a wall thickness of approximately 21 olI.

The tensile strength of this recycled leather is 48 kp/1.5 cm
Width and 3-point bending strength is 1-2 kF/1.5 cr
I got lucky with pr@.

Implementation flJ2 to lO1 Comparative Examples 1 to 6 A papermaking raw material slurry having the composition shown in Table 2 was used to obtain recycled leather having the physical properties shown in the same table.

(Margin below)

Claims (1)

[Scope of Claims] 1) Defibrated waste material mainly composed of chrome-tanned leather shavings and a carboxyl group (-COOH) based on α,β-unsaturated carboxylic acid of 1.4×10^ - A method for producing recycled leather from a slurry containing an aqueous emulsion of an anionic copolymer resin in a proportion of 2 moles or less. 2) The method according to claim 1, wherein the α,β-unsaturated carboxylic acid is a compound selected from acrylic acid, methacrylic acid, and itaconic acid. 3) The copolymer of the anionic resin aqueous emulsion consists of (a) 0 to 1.0% by weight of α,β-unsaturated carboxylic acid (b) acrylic acid alkyl ester (the number of carbon atoms in the alkyl group is 2 to 8) 40-55% by weight (c) 30-55% by weight of a monomer selected from methyl methacrylate, styrene, acrylonitrile (d) N-phenylmaleimide, N-methylolacrylamide, acrylamide, methacrylamide, 2-hydroxyalkyl acrylate (The number of carbon atoms in the alkyl group is 2 to 4) 100 parts by weight of a vinyl monomer mixture consisting of 1 to 10% by weight of a vinyl monomer selected from the group consisting of 2 to 4 carbon atoms is emulsified in the presence of 0.5 to 5 parts by weight of an anionic emulsifier. The method according to claim 1, which is a copolymer obtained by polymerization. 4) The anionic resin aqueous emulsion has a resin solid content of 8 to 50 parts by weight per 100 parts by weight of defibrated shaving waste.
2. The method according to claim 1, wherein the ingredients are blended in parts by weight.